This invention relates generally to sealing of phosphated coatings, and more particularly concerns improving the corrosions resistance of such coatings through use of solutions which do not prevent disposal problems.
Phosphate coatings on metals act to promote adhesion of enamel, paint, varnish, etc; however their corrosion resistance is less than desirable. In the past, compounds based on chromic acid or chromates have been employed as rinse additives to seal the metal and improve corrosion resistance of phosphated coatings; however, chromate rinses present waste disposal problems. Fluoride rinses are disclosed in U.S. Pat. No. 3,895,970; however, they are less advantageous than the rinses of the present invention.